Conventionally, there is known a riffel-type speaker configured to include a rectangular diaphragm and a linear voice coil arranged at the center of the diaphragm. For example, a speaker having a configuration of this kind is disclosed in a Patent Reference 1.
The speaker disclosed in the Patent Reference 1 includes: an upper and a lower magnetic circuits providing magnetic gaps parallel with each other and having opposite magnetic flux directions; a frame connected to the magnetic circuits and having an U-shaped section; a diaphragm supporting a voice coil substantially at its center and having an outer circumference supported by the frame; and a damper arranged below the voice coil and having an outer circumference attached to the frame. By this configuration, the minimum resonance frequency f0 can be lowered even if an elongated configuration with a narrow lateral width is employed, thereby improving the sound pressure characteristic.
Patent Reference 1: Japanese Patent Application Laid-open under No. H11-187484